Transmitting and receiving system



April 3 1926. 1,581,085

J. H. HAMMOND, JR

TRANSMITTING AND RECEIVING SYSTEM Origihal Filed May 13, 1920 INVEIV TOR W/W/W ZJZWW "TOR/UH. i

Patented Apr. 13, 1926.

UNITED STATES PATENT OFF-ICE.

TRANSMITTING AND RECEIVING SYSTEM.

Application filed Kay 13,1920, Serial 110,881,163. Renewed August 16, 1924.

invented certain new and useful I mprove-. ments in Transmitting and Receivmg Systems, of which the following is a specifica-.

tion. 7

One of the objects of the present invention is to provide means for transmitting a series of high frequency waves, for impressing a plurality of series of oscillations of different, secondary frequencies upon said series of waves, and for separately modifying the oscillations. A further object of the invention is ,to provide means for transmitting aplurality of signals or messages simultaneously and selectively receiving said signals or messages. A still further object of the invention is to provide means for receiving a series of high frequency waves modified at a plurality of secondary frequencies above audibility by series of oscillations, each of which is in turn separately modulated at an audio frequency, and selectively receiving the respective, modulated, secondary frequencies. The invention also aims to provide other improvements as will hereinafter appear.

In the accompanying drawing Fig. 1 represents diagrammatically one form of transmitting system embodying the present invention; and Fig. 2 represents diagrammatically one form of receiving system embodying the present invention. 7

Referring to Fig. 1 of the drawing, the

- transmitting system includes an open, aerial circuit 10 having an antenna 11, grounded at 12 and including a'secondary coil 13 of a transformer 14.

For impressing high frequency oscillations upon the aerial circuit 10 to produce a high frequency carrier wave, the secondary coil 13 is inductively coupled to an oscillating circuit 15 through a primary coil 16. A

condenser 20 is included in the circuit 15,

and the latter is connected to 21v source of current, such as an alternating curren'tgenerator 21, through suitable inductive resistances 22 and 23.:

To impress a secondary frequency or a )lurality of secondary frequencies upon the high frequency Wave of the aerial circuit 10, a closed circuit 24 is provided which is grounded at 25 and includes a thermionic valve 26 of any well known form. In the present instance, this valve 26' is of the evacuated glass bulb type having a plate clectrode 27 connected to the circuit 10;- a grid 28 included in the circuit 24, and a filament 29 also contained in the circuit 24 and heated by a battery 30in a well known manner. Preferably, the circuit 24' includes a plurality ofsecondary coils 31 and 32 in- 34 energized by the generator 41 will impress a seriesof oscillations of a second and different frequency upon the circuit 24.

For varying the amplitude of the two impressed series of oscillations two telephone transmitters 42 and 43 are included respec tively in the two circuits 33 and 34. Two speakers can simultaneously use the telephones 42 and 43. The vacuum tube 26 is so connected to the antenna that the carrier wave is modulated by the two series of oscillations produced by the high frequency generators 40 and 41 at two super-audible fre-' queucies. On these two series of oscillations there are impressed the individual speech modulations of the two speakersrespectively. Thus the energy transmitted from the antenna 11 is modified by the two frequencies produced by the alternators 40 and 41, and these two fre uencies in turn are modified in their amplitude by the sound waves actuating the telephone transmitters 42 and .43 in the respective circuits 33 and 34.

For receiving messages or signals trans--v mittedby theaboveascribed transmitting system a receiving, 0 en, aerial circuit 50 is provided comprising .an antenna 51- grounded at 52 and comprising a primary coil 530i a transformer 54. The primary coil 53 is inductivelycoupled to a secondary coil 55 included in a. closed, oscillatory circuit 56 tuned to the high frequency of the carrier wave transmitted from the antenna 11 with the alternator 21 as a source. A condenser 57 isalso included in the circuit 56. The oscillatory circuit 56 is connected at one side by means of branch conductors 60 and 61 respectively to grids 63 and 63' respectively of a suitable detector 64 which is here shown as of the evacuated bulb type. The other side of the circuit 56 is connected by a conductor 65 to the filament 66 of the detector 64. v

For selecting either of the received, modified, secondary frequencies, or selecting both simultaneously, the branch conductor 60 includes a closed, oscillatory circuit 7 tuned, for example, to the frequency of the oscillations produced by the alternator 40, while the branch conductor 61 includes a elosed, os-

I cillatory circuit 71, tuned tolthe frequency of the oscillations produced by the alternator 41. The circuit 70 includes a condenser 72 and is inductively coupled by a havinga condenser 84 and tuned to the same frequency as the circuit 71. This circuit 83 is arranged in a lead 85 connected to a plate electrode 86 of the detector 64. Thus the circuits 75 and 83 operating in conjunction with the detector 64 and the circuits 70 and 71 have a well understood regenerative ac-v tion. The detector 64 is arranged to control two circuits 90 and 91 having a common battery 92 and including respectively two telephone receivers 93 and 94, the former being connected to the circuit 75 and the latter to the circuit 83.

In the operation .of the system of the resent invention, it will be apparent.that 1t is possible to receive simultaneously the high frequency carrier wave and the two secondary, impressed frequencies, the former passing through both branches and 61. The latter with their respective audio-frequency modulations are selected through the action of the oscillatory circuits and 71 res ectively and the regenerative circuits 7 5 an 83. Since the reception of the signals or messages takes place by listening to the amplitude changes of the two secondary frequencies, it is obvious that the receiving operator at the. telephone 93 will hear the speech of one transmitting operator impressed upon one secondary frequency while t'he receiving operator at the telephone 94 will hear the speech of another transmitting operator impressed upon the other secondary frequency. The system is therefore arranged to simultaneously receive two or more messages at one time through a detector arranged. for common control.

Having thus fully what I claim is 1. A system forreceiving radiant energy in the formof a series of'oscillations having a predetermined high frequency and having impressed thereon a plurality of series of secondary oscillations of frequencies described my invention,

differing from each other and .from said high frequency,- each of said series of sec- 2. A system for the reception of radiantenergy in the-form of a series of oscillations having a predetermined high frequency and modified in accordancewith a plurality of series of secondary oscillations of frequencies differing, from each other and from said high frequency, the series of secondary oscillations having impressed thereon amplitude variations in accordance with a plurality of series of sound waves respectively, comprising a circuit responsive to said firstmentioned frequency, a single wave-responsive device controlled by said first mentioned circuit and having a corresponding plurality of input and output circuits, each of said output circuits being selectively responsive to one of said second-named frequencies, and means included in each of said output circuits for reproducing the sound waves.

3. A system for receiving radiant energy in the form ofhigh frequency oscillations having impressed thereon. a plurality of series of waves of different frequencies, each modulated in accordance with a series of waves of audible frequency comprising a circuit responsive to said first-mentioned frequency, a single electron-emitting device controlled by said first-mentioned circuit and having a corresponding plurality of input and output circuits, said output circuits being selectively responsive to currents of different frequencies corresponding respectively to said second-named frequencies, and means included in each of said output circuits for reproducing the respective series of waves of-audible frequency.

4. Apparatus for receiving relatively high frequency oscillations modified by a plurality of series of periodic variations of lower frequencies, differing from each other and each having impressed thereon amplitude variations, comprising a circuit responsive to said first-named frequency, a single Wave-responsive device controlled by said firstmentioned circuit and having a corresponding plurality of input and output circuits, each of said input circuits being tuned to respond to a different frequency, and each of the output circuits being tuned to respond to the frequency for which its respective input circuit is tuned and means included in each of said output 1 circuits for reproducing the impressed amplitude variations.

5. A s stem for signaling including means for pro ucing relatively high frequency oscillations, means for modulating said oscillations comprising a plurality of sources of alternating current of lower frequencies differing from each other, means for independently impressing amplitude variations on each of said alternating currents, means for receiving said oscillations including a circuit responsive to said first-named frequency, a single wave-responsive device controlled by sa1d first-mentioned ClIClllt' and having a corresponding plurality of input and output circuits, each of said input circuits being tuned to respond to a frequency corresponding to one of said second-named frequencies, and each of the output circuits being tuned to respond to the frequency for which its respective input circuit is tuned, and means included in each of said output circuits for reproducing the impressed amplitude variations.

6. A system for signaling including means for producing relatively high frequency oscillations, means for modulating said oscillations comprising a plurality of sources of alternating current of lower frequencics,dif-- circuits being tuned to respond to the frequency for which its respective input circuit is tuned, and means included in each of said out put circuits for reproducing the impressed, audible, am litude variations.

7 A system for signa ing including means for producing relatively hi h frequency oscillations, means for'mod ating said oscilv lations comprising a plurality of sources of alternating current of lowerfrequencies dif-.

fering from each other, means for independently impressing amplitude variations on each of said alternating currents, means for receiving said oscillations including a circuit responsive to said first-named I frequency, a single wave responsive device controlled by said first mentioned circuit and having a correspondin plurality of input and output circuits, sai input c1rcu1ts being tuned to respond to different frequencies, and each of the output circuits being tuned to respond to the frequency for which its respective input circuit is tuned, and means included in each of said output circuits for reproducing the impressed amplitude variations.

8. A system for the transmission of en'- ergy comprising means for transmitting radiant energy in such a form as to include a plurality of. series of periodic variations having different frequencies respectively, and means for receiving said energy including a wave-responsive device having a corresponding plurality of input and output circuits, said input circuits being tunedto respond to different frequencies, and, each of the output circuits being tuned to respond to the frequency for which its respective input circuit 1s tuned, and means included in each of said output circuits for reproducing the impressed amplitude variations.

9. Apparatus for receiving radiant energy of such a form as to include a plurality of series of periodic'variations having differ ent frequencies respectively, comprising means for receiving said energy including a wave-responsive device having a corresponding plurality of input and output circuits,

each of said output circuits being selectively responsive to a frequency corresponding to one of the series of periodic variations and including an indicating device.

10. A. system for receiving radiant energy in the form of high frequency oscillations having impressed thereon a series of periodic variations of lower frequency, comprising a detector having input and output circuits, a closed, oscillatory circuit connected in the input circuit of the detector and tuned to the frequency of the high frequency oscillations, and a second, closed oscillatory circuit connected in the input circuit of the detector and tuned to the frequency of said periodic variations.

11. A system for receiving radiant energy in the form of high frequency oscillations having impressed thereon a series of periodic variatlons of lower frequency, comprising a detector having input and output circuits and closed, oscillatory circuits connected in said input and output circuits respectively, said closed, oscillatory circuits being regeneratively coupled together and being tuned to the frequency of said periodic variations.

12. A system for receiving radiant energy comprising a vacuum tube detector and a plurality of pairs of circuits connected therewith, each pair including a grid-filament circuit and a plate-filament circuit, tunin elements connected with both the grid-filamcnt circuit and the plate-filament circuit of one pair of circuits to render such pair of circuits responsive to energy of a predeterspond to energy of different frequencies rei mined frequency and tuning elements conspectively.

n cted with the grid-filament circuit and Signed at New York in the county of New 10 plate-filament circuitof another pair of cir- York and State of New York this 12th day 5 wits and having different electrical conof May 1920.

stants from said first-mentioned tuning elemenis to cause said pairs of circuits to re-' JOHN HAYS HAMMOND, JR. 

